1. Field of the Invention
The present invention relates generally to the provision of a reusable "training" or "practice" round of ammunition that includes a reusable hollow casing, a reusable hollow projectile, and a reusable resilient connecting medium for releasably retaining the casing and projectile in assembled configuration until the round is chambered and fired. In preferred practice, the casing and the projectile have interfitting connecting portions that define coaxially extending surfaces that are brought into juxtaposition just as the assembly of the casing and the projectile are completed; and, the resilient connecting medium takes the form of a groove-mounted O-ring that is tightly clamped between the juxtaposed surfaces during assembly of the round. An optional aspect of the invention relates to the provision of one or more groove-carried O-rings that extend circumferentially about outer surface portions of the projectile of a practice round for engaging barrel rifling formations to impart spin to a fired projectile.
2. Prior Art
During the training of law enforcement and military personnel to fire 37 mm and 40 mm weapons of the type known as "gas guns" and "grenade launchers," it is desirable to minimize ammunition cost and attendant danger by using "training" or "practice" rounds rather than "live" ammunition during demonstration and practice firings of "these relatively large-bore guns. By practice-firing training rounds, personnel can become familiar with operation of the weapons; and, to the extent that the projectiles of training rounds are capable of properly simulating flight characteristics of live ammunition, proficiency can be developed in aiming and firing the weapons.
Because presently available training rounds for use with 37 mm and 40 mm weapons characteristically are neither inexpensive nor repeatedly reusable, the relatively high cost of training ammunition often stands as an obstacle to providing personnel who need to be proficient in the use of these weapons with frequent, regularly scheduled opportunities to practice-fire the weapons. Because many police departments have severely limited budgets for purchasing training rounds for large bore weapons, it often is the case that even those personnel who once had training in the use 37 mm and 40 mm weapons have not been provided with adequate opportunities to maintain their proficiency with these weapons by participating in regular, repeated target practice of the type that typically is needed to attain and maintain proficiency.
Another problem that often is encountered when utilizing training or practice rounds is that the materials from which the rounds are formed fail to provide projectiles that, when launched, properly simulate the flight trajectory and range of a live round. Thus, to the extent that training is conducted utilizing training rounds, often such training is not adequately realistic to permit personnel to become proficient in firing live rounds.
Still another problem that is encountered with present-day training ammunition is that, even when training rounds are intended to be "reusable," in actual practice one or more component parts of the rounds are found to crack, shatter or otherwise be rendered unusable after only a few firings. In many instances, so-called "reusable" training rounds break after only a single firing. Thus, there has been a long-standing need for training rounds formed from durable components that are repeatedly reusable, that properly simulate the flight characteristics of a live round of ammunition, and that can be repeatedly reused at a low cost per practice firing.
In concluding this discussion of present-day practices and other relevant aspects of the "prior art," it is desirable to briefly mention two additional topics. One has to do with the provision of ammunition with so-called "spin bands" for use with weapons having "rifled" barrels The other has to do with the limited use that has been made, to date, of so-called "O-rings" in the design and construction of ammunition.
It is known to provide rounds of ammunition with one or more rings of soft metal known as "spin bands" that engage rifling within the barrel of a weapon to impart spin to a fired projectile. Typically, such bands are formed from lengths of soft metal such as lead. Mounting portions of the bands typically are crimped into grooves that extend circumferentially about projectiles. When the projectiles are fired, the bands tend to be distorted as they are forced into engagement with barrel rifling. Present-day spin bands tend not to be reusable.
It also is known to utilize O-rings as component parts of various forms of ammunition. However, the function commonly performed O-ring components of ammunition is to provide fluid-tight "seals" between or among adjacently positioned components. The use of O-rings to provide seals does not teach or suggest the very different, nonconventional uses to which resilient O-rings are put in accordance with various aspects of the preferred practice of the present invention, as those who are skilled in the art readily will appreciate.